Abstract [en]

Contrast, noise and spatial resolution are fundamental physicalconcepts used to describe image quality. Contrast is one ofthe most important parameters in conventional film radiography.To facilitate the analysis of the radiographic contrast overa wide range of optical densities, an ivory wedge representativeof objects with marked tissue discontinuities has been constructed.It can be used either separately or included within a PMMA phantomrepresenting the middle face to simulate realistic scatter conditions.It is thus possible to investigate how radiographic contrastmay be influenced by kV setting, beam filtration, type of generator(constant potential or single pulse) and type of film. The phantomhas been used in optimising image quality relative to radiationrisk, with the radiographic contrast being determined both theoreticallyand experimentally in terms of type of film (D and E speed),radiation and object contrast. The importance of controllingphysical parameters when investigating image quality and howto achieve this using a well defined phantom is clearly demonstrated.